The molecular diffusivities of pyridine in the aqueous solutions as bulk liquid were extracted from the mutual diffusivity profile of the pyridine-water system on the basis that the molecular diffusivity of pyridine in the concentration range (100–200 mg/L) can be assumed constant and equal to the molecular diffusivity of pyri- dine at infinite dilution, which is equivalent in value to the mutual diffusivity at its infinite dilution [72].